Ruble was the best performing major currency of 2025, and it's easy to understand why

What Russia did is replace USD-denominated securities (treasuries, bonds, etc) with gold.

Gold is almost 40% of Russia's Central bank balance sheet, compare it to ≈20% for European Union, ≈16% for U.S. and ≈5% for China. This leaves Russia's central bank with a massive balance sheet capacity for the future and supports the Ruble price.

There's also the National Wealth Fund, which commits to buying gold when Urals oil is sold/traded above a certain price.